package org.ricks.asm;

public abstract class AnnotationVisitor {

    /**
     * The ASM API version implemented by this visitor. The value of this field must be one of the
     * {@code ASM}<i>x</i> values in {@link Opcodes}.
     */
    protected final int api;

    /**
     * The annotation visitor to which this visitor must delegate method calls. May be {@literal
     * null}.
     */
    protected AnnotationVisitor av;

    /**
     * Constructs a new {@link AnnotationVisitor}.
     *
     * @param api the ASM API version implemented by this visitor. Must be one of the {@code
     *     ASM}<i>x</i> values in {@link Opcodes}.
     */
    protected AnnotationVisitor(final int api) {
        this(api, null);
    }

    /**
     * Constructs a new {@link AnnotationVisitor}.
     *
     * @param api the ASM API version implemented by this visitor. Must be one of the {@code
     *     ASM}<i>x</i> values in {@link Opcodes}.
     * @param annotationVisitor the annotation visitor to which this visitor must delegate method
     *     calls. May be {@literal null}.
     */
    protected AnnotationVisitor(final int api, final AnnotationVisitor annotationVisitor) {
        if (api != Opcodes.ASM9
                && api != Opcodes.ASM8
                && api != Opcodes.ASM7
                && api != Opcodes.ASM6
                && api != Opcodes.ASM5
                && api != Opcodes.ASM4
                && api != Opcodes.ASM10_EXPERIMENTAL) {
            throw new IllegalArgumentException("Unsupported api " + api);
        }
        if (api == Opcodes.ASM10_EXPERIMENTAL) {
            Constants.checkAsmExperimental(this);
        }
        this.api = api;
        this.av = annotationVisitor;
    }

    /**
     * Visits a primitive value of the annotation.
     *
     * @param name the value name.
     * @param value the actual value, whose type must be {@link Byte}, {@link Boolean}, {@link
     *     Character}, {@link Short}, {@link Integer} , {@link Long}, {@link Float}, {@link Double},
     *     {@link String} or {@link Type} of {@link Type#OBJECT} or {@link Type#ARRAY} sort. This
     *     value can also be an array of byte, boolean, short, char, int, long, float or double values
     *     (this is equivalent to using {@link #visitArray} and visiting each array element in turn,
     *     but is more convenient).
     */
    public void visit(final String name, final Object value) {
        if (av != null) {
            av.visit(name, value);
        }
    }

    /**
     * Visits an enumeration value of the annotation.
     *
     * @param name the value name.
     * @param descriptor the class descriptor of the enumeration class.
     * @param value the actual enumeration value.
     */
    public void visitEnum(final String name, final String descriptor, final String value) {
        if (av != null) {
            av.visitEnum(name, descriptor, value);
        }
    }

    /**
     * Visits a nested annotation value of the annotation.
     *
     * @param name the value name.
     * @param descriptor the class descriptor of the nested annotation class.
     * @return a visitor to visit the actual nested annotation value, or {@literal null} if this
     *     visitor is not interested in visiting this nested annotation. <i>The nested annotation
     *     value must be fully visited before calling other methods on this annotation visitor</i>.
     */
    public AnnotationVisitor visitAnnotation(final String name, final String descriptor) {
        if (av != null) {
            return av.visitAnnotation(name, descriptor);
        }
        return null;
    }

    /**
     * Visits an array value of the annotation. Note that arrays of primitive values (such as byte,
     * boolean, short, char, int, long, float or double) can be passed as value to {@link #visit
     * visit}. This is what {@link ClassReader} does for non empty arrays of primitive values.
     *
     * @param name the value name.
     * @return a visitor to visit the actual array value elements, or {@literal null} if this visitor
     *     is not interested in visiting these values. The 'name' parameters passed to the methods of
     *     this visitor are ignored. <i>All the array values must be visited before calling other
     *     methods on this annotation visitor</i>.
     */
    public AnnotationVisitor visitArray(final String name) {
        if (av != null) {
            return av.visitArray(name);
        }
        return null;
    }

    /** Visits the end of the annotation. */
    public void visitEnd() {
        if (av != null) {
            av.visitEnd();
        }
    }
}